片段 getActivity() 中的 Android AlertDialog Builder 不起作用

Question

我尝试在 Fragment 中构建 AlertDialog，但找不到 AlertDialog Builder 的正确上下文。

public class LoginFragment extends Fragment {
public LoginFragment() {
    // Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_login, container, false);

    Button btnEnter = (Button) rootView.findViewById(R.id.btnEnter);

    // Listening to register new account link
    btnEnter.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {

        // if play name already exists
            AlertDialog dialog = new AlertDialog.Builder(getActivity())
                .setCancelable(false)
                .setIcon(R.drawable.login_icon)
                .setMessage("Player Name Already Exists. Please Find a New Name.")
                .setButton("Okay", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
            }).show();
        }
    });

    return rootView;
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
}

@Override
public void onDetach() {
    super.onDetach();
}

}

在这一行：

AlertDialog dialog = new AlertDialog.Builder(getActivity());

getActivity() 不起作用。它说“需要 AlertDialog，找到 AlertDialog.Builder”。我尝试过类似 this.getActivity() 和 getContext() 以及 getSupportFragmentManager() 之类的方法，所有这些都不起作用。我对此有些困惑。有人可以告诉我应该使用哪个以及为什么？

Answer 1

AlertDialog dialog = new AlertDialog.Builder(getActivity());

应该替换为

AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());